Sp.Gr. of Golf Cart 6v batteries

Like BFL said, you're in good shape. Mine are around 1.285 typically. BTW, once you figure out how you're batteries behave, you won't need to do hydrometer checks as often. My last check was February.

brulaz wrote:
Trailer came with 2 6v US2000 golf carts last fall. No idea what their actual age is.

Tried to take care of them with full re-charge the day after ~50% depletion (~12V) with Prog. Dyn. 6280, and later with built in tiny solar during storage.

Added larger solar and Rogue MPPT a month ago. Started doing Rogue's equalize at 15.3V for 2 hrs every few weeks then.

Finally got a half-way decent Sp. Gr. meter (glass tube with bobber) today and measured Sp. Gr of the battery cells: all three cells of Battery #1 (+12V terminal) are ~1.285, all 3 cells of battery # 2 (-12V terminal) are ~1.275. Temperature is 19C. Roque is in float mode at 13.1V.

No idea how accurate this Sp.Gr. meter is (auto store special), but at least it's consistent. All cells of the same battery give the same reading.

So what does it mean? I think both batts are fully charged. But should I be concerned that one has a slightly lower sp.gr.?

It doesn't matter that one is 80 and the other 75 when they are that old. Those both indicate your batts are in good shape for the shape they are in.

Suggest mark the batteries 1 and 2 with sticky tape or something, and keep a note of what the SG is now (call it your baseline SG for each battery) In future you can compare readings you get with baseline to see if they could do with more charging or if you are "there" and can quit.

Ignore RJ on this topic! :) He is saying that ignorance is bliss. Hydrometer owners know that can be a "fool's paradise." RJ is not a fool, so it is strange that he has chosen this attitude.

My three year old 6s, one pair of Interstate GC2 XHDs (232AH) and one pair of Exide 135s (226AH) today measured 1.300 in all cells of both pairs after some really nice days we are having this month on solar.
No equalizing, just reach 14.8v daily, then drops to 14.4 for the rest of the day.

The two used Trojan 12v T-1275s I got last year and "restored" are banked with the four 6s and are also doing nicely with their SGs at or near baseline. (The T-1275s take more charging than the 6s so to get them to full baseline means the 6s sit there losing water for a time with them getting to baseline SG earlier. I choose to just add water to the 6s and let the T-1275s "catch up" rather than lower the Float voltage so the T-1275s never get there while the 6s do. (One of the issues with mixing battery types, but easily overcome in this case.)

What if you didn't know there was such a thing as a hydrometer ? What if they were AGMs, all other things being the same, how would they be performing for you ?
Even the most sofistigated electronic battery testers now days, don't read specific gravity. Hydrometers are obsolete years ago already, dump it.

So what does it mean? I think both batts are fully charged. But should I be concerned that one has a slightly lower sp.gr.?

You could increase voltage on your equalize session to a higher voltage, say, 16V and observe current draw until it tapers to a low draw. This may net you .05-->.10 in SG and isn't a bad thing to do with an older battery.
In the grand scheme, your measurements are good and the difference between the two batteries is nothing to worry about.

The correct fully charged specific gravity of your 6-volt deep cycle battery is: 1.265
(will vary dependent on battery age, condition and ambient temperature)

Specific gravity should not be allowed to drop below 1.225.